Method and apparatus for fracturing connecting rods and the like

ABSTRACT

A process and apparatus for fracturing, into a bearing cap and a connecting rod, an integral preform which defines a cylindrical aperture and two spaced-apart bolt seat shoulders. A guide member defines a first guideway along which moves a first slide member, the latter in turn defining a second guideway parallel to the first, along which a second slide member moves. A split mandrel has an upper part fixed with respect to the first slide member and a lower part fixed with respect to the guide member. The split mandrel halves define an internal tapered passageway for receiving a wedge capable of forcing the mandrel halves apart. Projections on the second slide member contact the bolt seat shoulders when the cylindrical aperture of the preform receives the split mandrel, and means are provided for urging the second slide member toward the mandrel. When the wedge member enters the tapered passageway, forcing the mandrel parts apart and fracturing the preform, the bearing cap&#39;s contact with the projections and the upper part of the split mandrel securely holds the bearing cap in place. Further positional security is provided by static and dynamic locators which have a lateral pinching action on the bearing cap and on the connecting rod.

This application is a national phase filing of PCT international patentapplication No. PCT/US95/03620 filed on Mar. 22, 1995, which claimspriority of U.S. Ser. 08/220,490, now U.S. Pat. No. 5,503,317.

This invention relates to the fracture separation, into a bearing capand a connecting rod, of an integral preform, while ensuring that theseparated pieces will be capable of reunification, in a high productionenvironment.

BACKGROUND OF THIS INVENTION

Numerous methods have been employed to separate connecting rod preformsby fracturing, both in laboratory and production environments. Theseinclude cryogenic cooling or electron beam exposure to embrittle thefracture area, fracturing by wedge actuation of an expanding mandrel,and linear opposing pulling forces to separate the bearing cap from theconnecting rod preform. The following patents are representative of theprior art:

U.S. Pat. No. 4,569,109, issued Feb. 11, 1986;

U.S. Pat. No. 4,768,694, issued Sep. 6, 1988;

U.S. Pat. No. 4,993,134, issued Feb. 19, 1991.

Despite these prior developments, certain elements vital to fractureseparation continue to have the greatest influence on the quality of thefinished connecting rod. Two of these elements are:

(1) achieving simultaneous fracture along the crackling plane of bothlegs of the connecting rod. Failure to achieve simultaneous fracture islikely to result in plastic deformation of the crank bore and inhibitremating of the two parts;

(b) maintaining positive control over the position of the separatedbearing cap and connecting rod body, to ensure accurate micro-alignmentduring re-mating. Failure to do this may negate the inherent advantagesof fracture separation.

GENERAL DESCRIPTION OF THIS INVENTION

The present invention provides an apparatus and a process foraccomplishing the fracture separation, into a bearing cap and aconnecting rod, of an integral preform, the latter being composed ofpowdered metal, cast iron, forged steel, aluminum or any other materialsuitable for use as a connecting rod. The process of this invention isconducted under ambient conditions and requires no prior embrittlementof the preform, as called for by earlier developments utilizingcryogenic chilling or electron beam hardening.

However, a stress-riser is required to control the location of fractureinitiation (i.e. the location of the joint line). The stress-riser maybe provided in a prior process by way of (a) V-notch broaching or otherequivalent machining means, (b) laser etching, or (c) preforming astress-riser in the “green” preform prior to firing (baking) andforging.

The present process utilizes a work-holding fixture which retains andlocates the connecting rod preform with repspect to its manufacturingdatum features. The mechanism includes a dual slide ram coupled to aunilateral wedge interposed between a two-piece mandrel which, whenactivated, effects the fracture separation of the preform into a bearingcap and the connecting rod.

A further aspect of this process is the ability of the work-holdingfixture to locate the pre-separated connecting rod preform on themanufacturing datum features, and to maintain this location throughoutseparation and re-mating. This goal is achieved by constructing thework-holding feature on a precision slide. A lower portion of thework-holding fixture, which rigidly secures the connecting rod body, isaffixed to the slide and restrains the connecting rod against anymovement. The upper portion of the work-holding fixture, which locatesand retains the bearing cap of the ultimate connecting rod, is affixedto a slide saddle movable on the precision slide.

This arrangement allows the bearing cap to move independently of theconnecting rod body during separation, while continuing to maintain itsprecision location with respect to the connecting rod body. Thearrangement of the present invention further eliminates any tendency forthe bearing cap to rotate during separation, thus promoting simultaneousfracture of both of the connecting rod legs. The re-mating of theseparated bearing cap to the connecting rod body is passivelyaccomplished by spring loading the upper portion of the work-holdingfixture to return it to its pre-fracture position. Subsequent to thefracture separation and re-mating of the bipartite connecting rod, thework-holding fixture, with is re-mated connecting rod still retained andlocated, can index out of the separation area for fastener insertion andfurther processing as required.

More particularly, this invention provides an apparatus for the fractureseparation, into a bearing cap and a connecting rod, of an integralpreform which is configured to define a cylindrical aperture and twospaced-apart bolt seat shoulders, the apparatus comprising:

a base member

a guide member fixed with respect to said base member, the guide memberdefining a first guideway extending in a first direction,

a first slide member mounted to said guide member for sliding movementalong said first guideway in said first direction, the first slidemember defining a second guideway also extending in said firstdirection,

a second slide member mounted to said first slide member for slidingmovement with respect to said first slide member along said secondguideway in said first direction,

a mandrel which is split to define an upper part fixed with respect tothe first slide member and a lower part fixed with respect to said basemember, said upper part being movable between a first position in whichit is spaced away from the lower part and a second position in which itis juxtaposed against the lower part to define a substantiallycylindrical body having its axis lying substantially in a seconddirection perpendicular to said first direction, movement of said upperpart being simultaneous with movement of the first slide member alongthe first guideway with respect to said guide member, the upper andlower parts of said mandrel defining an internal tapered passageway,

a wedge member adapted, when the upper part is in its second position,to enter said tapered passageway and force said mandrel parts apart,power means for moving said wedge member, projections defined by saidsecond slide member and adapted to contact the bolt seat shoulders of anintegral preform while the cylindrical aperture thereof receives thesplit mandrel, and means for selectively urging the second slide membertoward the mandrel, thereby securely holding the integral preform inplace, whereby the wedge member can enter the tapered passageway,forcing the mandrel parts apart and fracturing the preform into abearing cap and a connecting rod.

Further, this invention provides a process for the fracture separation,into a bearing cap and a connecting rod, of an integral preform which isconfigured to define a cylindrical aperture and two spaced-apart boltseat shoulders, the process comprising:

a) fitting they cylindrical aperture of the preform over a substantiallycylindrical mandrel which includes separate upper and lower parts,

b) holding the preform in place over the mandrel by pressing against thebolt seat shoulders in the direction toward the mandrel, and

c) forcing the mandrel parts apart while holding the preform in place,thereby to fracture the preform into a bearing cap and a connecting rod.

BRIEF DESCRIPTION OF THE DRAWINGS

One embodiment of this invention is illustrated in the accompanyingdrawings, in which like numerals denote like parts throughout theseveral views, and in which:

FIG. 1 is an elevational view looking at the front of the separationstation in a direction perpendicular to the direction of transfer,

FIG. 2 is a side elevational view, looking at the separation stationfrom a direction at right angles to the direction of FIG. 1, and ispartly broken away to show a section along the line 2—2 in FIG. 3;

FIG. 3 is a horizontal sectional view taken at the line 3—3 in FIG. 2,and the line 3—3 in FIG. 1; and

FIG. 4 is a view similar to that of FIG. 2, showing a variant of theelement causing the fracture separation.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates, in broken lines, a pre-separated preform 1Aintegrally incorporating a connecting rod 1 and a bearing cap 2, locatedand secured in a separation station work-holding fixture 3. It is to benoted that the preform 1A is configured to define a cylindrical aperture6 and two spaced-apart bolt seat shoulders 8 and 9, this being thetypical constriction.

One of the key features of the fixture 3 is the attainment of athree-point, wedge-locked retention for the bearing cap 2, both beforeand after fracturing. This is accomplished through the use of a smallslide assembly 4, which is best understood by comparing FIGS. 2 and 3.

A slide unit 21 is mounted for horizontal movement along the directionof the arrow 21A. Secured to the slide unit is a base member 30 which isintegral with the lower part 19 of a split mandrel (the remainder ofwhich will be described subsequently), and a guide member 18. Defined bythe guide member 18 is a first guideway 18B which has two oppositelyextending rectangular recesses 18A (See FIG. 3). The guideway 18Bextends in a direction perpendicular to the arrow 21A.

A first slide member 5 is mounted to the guide member 18 for slidingmovement along the first guideway 18B in the vertical direction (arrow5A in the drawings), and itself contributes to defining a secondguideway 5B, parallel with the direction of the first guideway. Thesecond guideway 5B extends in the vertical direction intermediatelateral edges 5C of the first slide member 5. In FIG. 3, which is ahorizontal section through the upper part of the assembly shown in FIG.2, a second slide member 10 of rectangular section in its upper portionis trapped between the first slide member 5 and a slide assembly cover12. In FIG. 3, the cover 12 defines a rectangular recess 12A and haslateral projections 12B for securely locating the cover 12 on the firstslide member 5. As can also be seen in FIGS. 1 and 3, threaded fasteners13A are utilized to secure the cover 12 against the first slide member5.

As illustrated in FIG. 2, the first slide member 5 integrally supportsan upper part 7A of a split mandrel 7, from which it will be understoodthat, when the first slide member 5 moves upwardly with respect to theguide member 18, the upper part 7A of the split mandrel 7 moves upwardlyaway from the lower part 19. It will further be noted that the axis ofthe split mandrel 7 lies in a direction substantially parallel to thearrow 21A, and is thus substantially perpendicular to the first guideway18B.

As further illustrated in FIG. 2, the upper and lower parts 7A and 19 ofthe mandrel 7 together define an internal tapered passageway shown inbroken lines at 19A, the passageway 19A being such as to accept a wedgemember 20 which, when driven to the left in FIG. 2, forces the mandrelparts 7A and 19 apart. It is to be noted that the passageway 19A has asubstantially horizontal lower portion 19B and a sloping upper portion19C. and that the leftward end of the wedge member 20 is correspondinglyconfigured. The purpose for this configuration is to avoid downwardforce against the lower part 19, and to maximize upward force againstthe upper part 7A.

Power means for moving the wedge member 20 in FIG. 2 is illustratedschematically as a hydraulic or pneumatic cylinder 32. As analternative, the wedge member 20 may be actuated by a slaved springmotion of known construction (not illustrated).

In an alternative construction, illustrated in broken lines in FIG. 4, awedge 20A can first come into direct contact with the tapered passagewayat a low force level, creating a preload upon the contact surfaces ofthe internal tapered passageway, whereupon a separate high-velocity ram33 could impact upon the wedge 20A, thus causing separation of thepreform into a cap and a rod. The pre-load by the wedge has the effectof taking up all slack, and leaving no free travel or lost motion in theupper and lower parts 7 and 19 defining the internal tapered passageway19A. In FIG. 4, the ram 33 is the end of a piston 33A moving in acylinder 33B. The position of the wedge 20A is controlled by anauxiliary cylinder 23 acting on a schematically illustrated flange 24secured to the wedge 20A.

Referring now to FIGS. 1 and 2, the second slide member 10 has a widenedportion 34 at the bottom, the portion 34 supporting projections 36 and38 which are adapted to contact the bolt seat shoulders 8 and 9 whilethe cylindrical aperture 6 in a preform 1A receives the split mandrel 7.

Means are provided, utilizing a camming member 11, for selectivelyurging the second slide member 10 toward the mandrel 7, thereby securelyholding the integral preform 1A in place. In FIG. 1, short hatch lineson portions 7A, 36 and 38 show the three-point “capture” of the upperpart of the preform 1A.

It will now be understood that, when the wedge member 20 enters thetapered passageway 19A, it forces the mandrel part 7A upwardly away fromthe part 19, thereby fracturing the preform 1A into a bearing cap and aconnecting rod. The camming member 11 will now be described in greaterdetail. The cover

12 defines a horizontal, rectangular passage 11A to either side of therecess 12A. The camming member 11 is a Z-shaped cam adapted to be movedby a force along the arrow 13. The upper part of the second slide member10 is machined to define a sloping passageway 40 for receiving a centralpart 42 of the cam, having the same slope as the passageway 40. It willbe understood that, as the camming member 11 moves leftwardly (as seenin FIG. 1), the second slide member 10 will move downwardly.

Illustrated schematically in FIG. 1 are locate and retention locators14-17. The locators 14 and 15 are fixed or static, whereas the retainers16 and 17 are dynamic clamps that apply a constant force leftwardly onthe preform, seating it firmly against the locators 14 and 15.

More particularly, the locators 14-17 include a first static locator 14adapted to contact one side of the portion of the preform 1A which isintended to become the bearing cap, and a second static locator adaptedto contact one side of the portion of the preform 1A intended to becomethe connecting rod. On the right in FIG. 1, the dynamic locator 16 isadapted to contact the other side of the portion of the preform 1A whichis intended to become the bearing cap, while the second dynamic locator17 is adapted to contact the other side of the portion of the preform 1Awhich is intended to become the connecting rod. The dynamic locators 16and 17 can be urged leftwardly by the use of resilient means, such assprings. The locators 14 and 16 are mounted on the first slide member 5while the locators 15 and 17 are mounted on the base member 30. It willthus be seen that, even though the fixture 3 constitutes a part carrieris used for transferring the connecting rod from one machine station toanother, the locators remain engaged with the preform (the connectingrod components) throughout the fracture and separation cycle.

Utilization of the illustrated apparatus may be defined as a process forthe fracture separation, into a bearing cap and the connecting rod, ofan integral preform configured to define a cylindrical aperture and twospaced-apart bolt seat shoulders. The process involves first fitting thecylindrical aperture of the preform 1A over the substantiallycylindrical mandrel 7 that includes separate upper and lower parts 7Aand 19 respectively, then holding the preform 1A in place on the mandrel7 by causing the projections 36 and 38 to press downwardly against thebolt seat shoulders 8 and 9 respectively in the direction toward themandrel than forcing the parts 7A and 19 apart (while holding thepreform 1A in place) thereby fracturing the preform 1A into a bearingcap 2 and a connecting rod 1. Upon fracture, caused by the high-velocityof the wedge member 20 entering between the mandrel halves 7A and 19,the following portions move vertically upward: the first slide member 5with its integral part 7A of the split mandrel 7; the cover 12, thesecond slide member 10, the cam member 42, the locators 14 and 16, andthe bearing cap 2 (which has been split from the connecting rod 1). Thefollowing parts remain stationary: the lower part 19 of the expandingmandrel 7, the guide member 18, the base member 30 and the slide unit21.

Immediately upon completion of fracture separation, the wedge member 20is withdrawn from between the mandrel halves 7A and 19, allowing thefirst slide member 5 to return to its pre-separation position. Actuationto return the first slide member 5 downwardly can employ any linearforce device shown schematically at 44 springs, cylinders, etc.), orgravitation.

It will no be understood that the apparatus and process described aboveallow the bearing cap 2 to be fracture-separated from the connecting rodbody 1, while all throughout the separation and re-mating process thelocation uniqueness of the bearing cap 2 with respect to the connectingrod body 1 is maintained. With respect to the slide unit 21 seen in FIG.2, its purpose is 1) to bring the equipment required to separate andre-mate the connecting rod bipartite while it is located and retained inthe part carrier, and 2) to perform separation and re-mating, and thenwithdraw from the connecting rod bipartite, leaving it located andretained as it was prior to separation.

While this invention has been described and illustrated with theconnecting rod preform 1A in a vertical attitude, the particular partattitude is not a limitation of this invention. The process outlinedabove can be carried out with the connecting rod in any desiredattitude. Of course, the various slides, actuators, clamps, locators anddirections of motion, as previously described, would change theirattitudes in a similar way, in order to keep the relative motions anddirections consistent.

A detailed description of the process follows:

Firstly, the locators 14-17 are activated to grip the preform.

Secondly, with the second slide member 10 withdrawn upwardly such thatthe projections 36 and 38 do not interfere, the preform aperture 6 isengaged with the split mandrel 7 and the ram slide assembly by a linearmotion, with the split mandrel parts 7A and 19 being juxtaposed againsteach other.

Next, the three-point retention of the connecting rod bearing cap isactivated, this taking place between the cap half 7A of the splitmandrel 7 and the projections 36 and 38, which contact the bolt seatshoulders.

Then, the wedge member 20 or the wedge 20A is activated to split themandrel 7, following which the wedge member 20 or wedge 20A iswithdrawn.

Then, the bearing cap retention constituted by the projections 36 and 38is disengaged.

Then, the split mandrel and the ram slide assembly is disengaged fromthe connecting rod by moving the slide unit 21 (illustrated in FIG. 2).

Finally, the locators 14-17 are disengaged at the point of removal ofthe 2-piece preform which has been reassembled using two bolts.

While one embodiment of this invention has been illustrated in theaccompanying drawings and described hereinabove, it will be evident tothose skilled in the art that changes and modifications may be madetherein without departing from the essence of this invention, as setforth in the appended claims.

What is claimed is:
 1. An apparatus for separation of an integralpre-form into a bearing cap and a connecting rod having a cylindricalaperture and two spaced apart bolt seat shoulders, the apparatuscomprising: a base member; a guide member fixed with respect to saidbase member, said guide member defining a first guideway extending in afirst direction; a first slide member having lateral edges, said firstslide member mounted to said guide member for sliding movement in saidfirst guideway in said first direction, said first slide member defininga second guideway also extending in said first direction intermediatesaid lateral edges of said first slide member; a second slide membermounted to said first slide member for sliding movement with respect tosaid first slide member in said second guideway in said first direction;a mandrel which is split to define a cap part fixed with respect to saidfirst slide member and a body part fixed with respect to said basemember, said cap part being movable between a first position spaced awayfrom said body part and a second position disposed adjacent said bodypart to define a substantially cylindrical body having an axis lyingsubstantially in a second direction perpendicular to said firstdirection, movement of said cap part being simultaneous with movement ofsaid first slide member along said first guideway with respect to saidguide member, said cap and body parts of said mandrel defining aninternal tapered passageway; a wedge member movable into said taperedpassageway when said cap part is in said second position to force saidmandrel parts apart; a power drive for moving said wedge member; saidsecond slide member including a first and a second hold down portionmechanically connected such that said hold down portions move defendantupon each other, said second slide member operable to bring said firstand said second hold down portion into contact with the bolt seatshoulders on the integral preform when the cylindrical aperture thereofreceives said split mandrel; a structure urging said second slide membertoward said mandrel, thereby securely holding the integral preform inplace; and movement of said wedge member through said tapered passagewayforcing said mandrel parts apart and fracturing said preform into thebearing cap and the connecting rod.
 2. An apparatus as recited in claim1, wherein said first and second hold down portions move as an integralone-piece part.
 3. An apparatus as recited in claim 2, wherein saidsecond slide member includes a connecting portion integrally connectingsaid first and second hold down portions, said structure urging saidconnecting portion.
 4. An apparatus as recited in claim 1, wherein saidstructure includes a cam surface forcing said first and second hold downportions toward said mandrel.
 5. An apparatus as recited in claim 4,wherein said structure includes a member which slides in a directiongenerally transverse to movement of said first and second hold downportions, and said clam surface thus urging said first and second holddown portions toward said mandrel.
 6. An apparatus for separation of anintegral pre-form into a bearing cap and a connecting rod having acylindrical aperture and two spaced apart bolt seat shoulders, theapparatus comprising: a split mandrel split to define a first mandrelpart and a second mandrel part defining a passageway therebetween; abase integrally formed with said first mandrel part, said baseintegrally formed with a guide extending in a first direction, saidguide defining a first guideway extending in said first direction; amandrel slide having lateral edges integrally formed with said secondmandrel part, said mandrel slide mounted in said first guideway forsliding movement along said guide in said first direction, said mandrelslide defining a second guideway also extending in said first directionintermediate said lateral edges of said mandrel slide; a clamp slidemounted in said second guideway for sliding movement in said firstdirection, said clamp slide having a first and a second hold downportion mechanically connected such that said hold down portions movedependant upon each other, said second slide member operable to bringsaid first and said second hold down portion into contact with at leastone of the bolt seat shoulders on the integral preform when thecylindrical aperture thereof receives said split mandrel; said secondmandrel part being movable between a first position spaced away fromsaid first mandrel part and a second position disposed adjacent saidfirst mandrel part to define a substantially cylindrical body having anaxis lying substantially in a second direction perpendicular to saidfirst direction, movement of said second mandrel part being simultaneouswith movement of said mandrel slide along said first guideway withrespect to said guide; an inclined surface disposed between said clampslide and said mandrel slide, movement of said inclined surface in athird direction perpendicular to said first and second directions urgingsaid clamp slide toward said mandrel, thereby securely holding theintegral preform in place; and a wedge selectively entering saidpassageway to force said first mandrel part and said second mandrel partapart in said first direction.
 7. A method as set forth in claim 6,wherein said first and second hold down portions are integral.